[Bug c/25975] Problems with -ffast-math and isnan

[Bug c/25975] Problems with -ffast-math and isnan

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ejtttje at gmail dot com

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-10-17 07:12:38 UTC ---
*** Bug 50724 has been marked as a duplicate of this bug. ***

[Bug c/25975] Problems with -ffast-math and isnan

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-17 15:43:58 UTC ---
*** Bug 50724 has been marked as a duplicate of this bug. ***

[Bug c/25975] Problems with -ffast-math and isnan

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-17 16:49:03 UTC ---
*** Bug 50724 has been marked as a duplicate of this bug. ***

[Bug c/25975] Problems with -ffast-math and isnan

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

--- Comment #8 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-17 18:53:56 UTC ---
*** Bug 50724 has been marked as a duplicate of this bug. ***

[Bug c/25975] Problems with -ffast-math and isnan

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-10-17 19:25:07 UTC ---
*** Bug 50724 has been marked as a duplicate of this bug. ***

[Bug c/25975] Problems with -ffast-math and isnan

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-17 21:05:02 UTC ---
*** Bug 50724 has been marked as a duplicate of this bug. ***

[Bug c/25975] Problems with -ffast-math and isnan

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
*** Bug 60237 has been marked as a duplicate of this bug. ***

[Bug c/25975] Problems with -ffast-math and isnan

[terra at gnome dot org]

------- Comment #4 from terra at gnome dot org  2006-01-26 17:22 -------
ok, thanks.  I'll prevent this by checking for __FAST_MATH__ in my code.
One could argue for a warning like

nan.c:13: warning: comparison is always false due to limited range of data type

for use of isnan and similarly (with true) for finite.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

[Bug c/25975] Problems with -ffast-math and isnan

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2006-01-26 14:47 -------
-ffast-math
Sets -fno-math-errno, -funsafe-math-optimizations, 
-fno-trapping-math, -ffinite-math-only, -fno-rounding-math, -fno-signaling-nans
and fcx-limited-range.
This option causes the preprocessor macro __FAST_MATH__ to be defined.

This option should never be turned on by any -O option since it can result in
incorrect output for programs which depend on an exact implementation of IEEE
or ISO rules/specifications for math functions. 


-ffinite-math-only
Allow optimizations for floating-point arithmetic that assume that arguments
and results are not NaNs or +-Infs.
This option should never be turned on by any -O option since it can result in
incorrect output for programs which depend on an exact implementation of IEEE
or ISO rules/specifications.

The default is -fno-finite-math-only. 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

[Bug c/25975] Problems with -ffast-math and isnan

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-01-26 14:44 -------
Please read the docs about -ffast-math.  It enables the option
-ffinite-math-only which means no NaNs.


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975

[Bug c/25975] Problems with -ffast-math and isnan

[terra at gnome dot org]

------- Comment #1 from terra at gnome dot org  2006-01-26 14:43 -------
Created an attachment (id=10732)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10732&action=view)
Output from "gcc-4.0.2 -E -ffast-math nan.c"

> gcc-4.0.2 -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../../gcc-4.0.2/configure --enable-languages=c,c++,f95
--prefix=/usr/local/products/gcc/4.0.2 --with-gnu-as
--with-as=/usr/local/products/gcc/binutils-2.16/bin/as --with-gnu-ld
--with-ld=/usr/local/products/gcc/binutils-2.16/bin/ld
Thread model: posix
gcc version 4.0.2


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25975